What Pittsburgh’s Fern Hollow Bridge Collapse Can Tell Us About Bridges in Pennsylvania

Nearly 20% of Pennsylvania bridges were in poor condition in a 2018 review by the Pittsburgh Chapter of the American Society of Civil Engineers.

(Pittsburgh) – Friday’s collapse of the city-owned Fern Hollow Bridge sparked concerns about thousands of bridges across the state of Pennsylvania, nearly 20% of which were in poor condition as of a 2018 report by the Pittsburgh Chapter of the American Society of Civil Engineers.

According to the Pennsylvania Department of Transportation, the Fern Hollow Bridge is just one of 175 state or local bridges in poor condition in Allegheny County alone.

Pittsburgh City Comptroller Michael Lamb said that given the many bridges and other infrastructure assets in the area that need special attention, “it’s really no surprise that something like this could happen. produce”.

He urged the city and county to review other bridges also deemed to be in poor condition because “there’s a good chance it will happen again.”

However, former Pittsburgh ASCE President Jonathan Shimko cautioned against panicking or thinking that “our entire infrastructure is in a state of imminent failure, because it is not.”

the Fern Hollow’s overall rating was “Poor”, but that’s because “engineers are inherently risk averse,” Shimko said. If there is one element of the bridge that gets a bad score, it will determine the overall score of the bridge, he said.

Guidelines for evaluating a bridge are shared and enforced by state and federal agencies, including PennDOT, even if an inspection is performed by a third-party contractor. They use a scorecard which ranges from 0 to 9, with 0 being the worst, for “failure, bridge is out of service and beyond corrective action”.

The part of the Fern Hollow Bridge that actually carries traffic – the deck – and the infrastructure below – the superstructure – both scored a ‘4’ under these guidelines, meaning their deterioration had been ‘advanced’. However, the structures that support these two components – the substructure – were rated ‘6’ or satisfactory with ‘minor deterioration’.

While PennDOT keeps records on state bridges, Fern Hollow is owned and maintained by the city. The bridge was last inspected in the fall of 2021 by a third-party contractor, said Pittsburgh City Council Corey O’Connor; he couldn’t remember who. WESA was unable to immediately obtain the most recent report. O’Connor told WESA that although the bridge was known to be in poor condition, “there was no indication that we should close it”.

PennDOT and the US Department of Transportation’s Federal Highway Administration maintain a record of bridge inspections. At the federal level, this is called the National Bridge Inventory; it classifies various parts of the bridge—elements—as falling into four categories called “condition states”.

In 2020, four steel columns that support the Fern Hollow Bridge were classified as “condition status 4”. On the National Bridge Inventory website, this is annotated as “severe”, but a technical guide provides a prescribed set of actions rather than a description.

The American Association of State Highway and Transportation Officials, AASHTO, Bridge Member Inspection Manual defines condition status 4 for steel columns as may require “structural review” to gather additional information.

Neither PennDOT officials nor officials from the U.S. Department of Transportation or the Federal Highway Administration responded to questions Friday about the differences between state and federal guidelines and their implications.

“The correct assessment of the condition of bridge elements is the cornerstone of good bridge management,” reads the introduction to the AASHTO manual.

When asked what might have contributed to the deterioration of the bridge, ASCE’s Shimko said it would not be appropriate to comment immediately as the focus must be on securing the site. However, he noted that many infrastructure failures, such as the sinkhole that opened in downtown Pittsburgh in 2019result not from a single actor or event, but from the culmination of a number of events.

“Many of which are the out-of-sight and out-of-mind nature of our infrastructure,” he said. “In a bridge there is a lot of steel, but often it is wrapped in concrete or its supports are covered with a lot of soil.”

It is therefore difficult to predict or know what the conditions are without “money and investment to ensure that we can maintain what we have built”.

Paying to fix all the bridges of concern in Pennsylvania is an expensive proposition. President Joe Biden’s infrastructure bill will provide $1.6 billion in bridge funding to the state, and during a visit to Pittsburgh on Friday, he pledged to “fix them all.” Yet there is more than 4,000 public and local bridges in poor condition.

Although the state has reduced the number of structurally deficient bridges, much of the funding that could have been used to address aging roads and bridges was used to fund the state police for much of the last decade.

The potential cost to replace Fern Hollow Bridge is unknown, and Lamb didn’t want to speculate. He was adamant, however, that the primary source of funding would not be the new federal kitty.

“There are other sources of funding for emergencies like this,” he said, citing programs from the U.S. Department of Transportation, the Federal Highway Administration and PennDOT.

For now, local and state officials say they are focused on finding out what caused the Fern Hollow Bridge to collapse. A National Transportation Safety Board response team arrived at the scene Friday afternoon. NTSB President Jennifer Homendy said the investigation would take months.

Ariel Worthy of WESA contributed to this report.

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